The present invention relates to an apparatus for cleaning the interior of a conduit line while the conduit is carrying a fluid under pressure. More specifically, the present invention is directed to apparatus for injecting into the sealed conduit line a cleaning element termed a "pig" or other similar cleaning element which is carried along the conduit by the fluid flowing therethrough and during its travel cleans the walls of the conduit of materials that accumulate over time.
In the past, the pipeline industry has employed a number of devices to clean out the interior of lines that carry natural gas, oil and chemicals from one point to another. A number of these devices have required close monitoring and several workers to assure proper operation of the cleaning device. For relatively large diameter pipelines, such as, for example, those on the order of one foot or more in diameter, it has been necessary to close down the pipe and drain it of its contents before a mechanical scraping device could be passed along the conduit to carry out the cleaning operation. In view of the relatively large cross-sectional area of such conduits, the cleaning operations could be carried out at intervals that were sufficiently spaced apart so that the economic consequences of a complete shutdown of the pipeline could be tolerated. However, with smaller diameter pipelines, and particularly those operating with certain types of products such as those carrying oil having a relatively high paraffin content, water condensate or other types of materials that would tend to participate out of the flow, substantially more frequent cleaning of the pipeline would be required. This is particularly true in northerly climates where exposed sections of the pipeline were subjected to freezing temperatures. In such environments, frequent and regular periodic traversal of the pipeline by a cleaning element such as a pig is required to maintain safe and economical operation of a pipeline. However, where the pipeline extends through remote or inaccessible areas, there is presently no satisfactory apparatus available that can be both reliably operated by a timing mechanism and still be operated by remote control to dispense and retrieve a cleaning element along a selected length of a pipeline. In a number of the manually operable cleaning systems, a worker must be present at the pig launch site to make sure that the pig is properly loaded and actually launched. Where the pipeline runs through remote areas, the cost of having one or more workers travel to the launch site can render the use of such cleaning devices prohibitive.
The present invention overcomes the foregoing difficulties and provides a very effective cleaning element launching and recovery or retrieving stations which can be operated very efficiently by remote control or by a timing device to periodically dispense and retrieve a cleaning element and one which does not require the presence of an operator for initiation or termination of a cleaning cycle.
In a preferred embodiment, the present invention provides a casing that is connected to the flow path of a conduit. The casing houses an injector member which has a carrier portion for receiving and holding a cleaning element which is preferably a spherical member of a diameter such as to closely interfit with the interior of the pipe to be cleaned. An actuating device which may be remotely controlled moves the injector member from a retracted position where the casing is sealed off from direct contact with the flow to an injected position where the carrier portion moves across the flow path to expose the cleaning element to the fluid flowing through the conduit whereby the cleaning element is carried off the carrier portion of the injector member and passed along the conduit to effect cleaning of the wall of the conduit. Downstream at a selected position, a retrieving apparatus is provided which includes a connection member which houses a valve which is operable to open and close a discharge opening immediately upstream of an obstacle which prevents a cleaning element from passing further down the conduit. The cross-sectional area of the discharge opening and the conduit connected thereto is larger than the cross-sectional area of the conduit so that the predominant flow when the valve is open is into the discharge opening. Downstream of the conduit connected to the discharge opening, a branch is provided. Vertically below the discharge opening and below the branch a storage tank is connected for collecting the fluid passing through the discharge opening when the valve is open. A barrier member such as a screen is permanently positioned across the conduit leading to the storage tank. At the branch, a second conduit leads to a storage barrel for collecting the cleaning elements passed through the discharge opening.
The arrangement of the present invention will permit rapid installation of the launching and retrieving assemblies at desired locations along the length of pipeline and an apparatus where both the launching of the cleaning elements as well as their retrieval can be accomplished by remote control, by a timing mechanism or by a mechanism that is sensitive to a condition of the pipeline such as fluid velocity or fluid pressure.